What? A $90 rent is 'well worth it'? If all you had was a sawsall you could have bought an angle grinder and a dozen cutoff wheels for that and had change left over, and a great tool for the future when done.

I love the loan a tool programs, save you from having to buy your own when you really only need it once, plus if you need it again, borrow it again. Simple. Plus if you get the right tool for the job, you don't have to buy an angle grinder and risk messing something up. Just my opinion.